IH: Engine Mechanicals

Cam Gear Selection for Quiet Operation

Timing gears for 1000, 1200 and 1340 models are originally installed and are supplied through parts order in matched sets to provide the proper gear lash (tooth clearance) for quiet operation. Select gears were also made for all models (1954-1979) 1)

Gear Measurements:

Cam gears for late model 1200, 1340 and l000 engines are color coded according to their diameter size as measured with special gauge pins.

The gear diameter is measured with a micrometer across .105“ diameter gauge pins (95632-79) on opposite sides of the gear. The pins fit between the contacting surfaces of the gear teeth (laid longways). Gear diameter should be measured in at least 2 places and 90° apart.

Original gears may be different sizes, (different color codes) to produce a properly matched set at the factory in any one engine while parts order matched gear sets are of one color. These were not happy-go-lucky dimensions.

Replacing worn gears:

Although all gears in the same engine (from the factory) are matched for proper fit, instances may occur where gears become worn and (excessive tooth clearance) produce a rattling noise particularly noticeable at the gear case cover at low RPMs. In such cases, a larger gear size can be selected to reduce the tooth clearances between the mating gears for quieter operation.

Procedure:

In 1000cc engines with 4 matched cam gears, it is recommended to increase the size of gears 1 and 3 by one color code (but no more than two size increases should be made before also increasing the pinion and intermediate gears). Then, run the engine to check for noise. However, if a gear whine or howl is produced by a size increase, it indicates that there is not enough tooth clearance and the size of the affected gears must be reduced.

With gear noises, in general, an increase in gear size will reduce rattle while a decrease in gear size will reduce gear whine or howl.

It is possible that gear whine or howl may be present to some extent in a new engine and may not disappear during break-in. A mild whine is acceptable, but if excessive, the gear train can be “fine-tuned” by using smaller size gears as described before.

An Alternative Method of Gear Selection requires removal of the push rods, tappet blocks and spark plugs. Check for gear tooth tightness by moving gear back and forth with a screwdriver and noting the resistance to movement. Do this for several positions (rotate flywheels). On the average, there should be a slight drag. The gear should not be too tight at any one spot which would indicate that the gear is out of round.

Color coding system:

Different gear (including cams, pinion, intermediate and generator drive gear) diameters were cut to a specific dimension with a base dim and an oversized dim for each color (0.001” apart). The base dim of the next color up was the same as the oversized dim for the previous color.

Some gears were cut to a standard dimension while specific gears were duplicated in multiple dimensions as the chart below shows. These specific gears were selected for different year models and design went all the way back to 1954 K models. Each Sportster year model selected had a color code starting with brown and ending with black:

Gear Dimension Changes by Color Code

Brown → Black denotes ranges starting with the smallest and increasing in size to largest dimension.

Brown

Blue

Red

White

Green

Yellow

Black

.000 - .001

.001 - .002

.002 - .003

.003 - .004

.004 - .005

.005 - .006

.006 - .007

Brown ← Black denotes ranges starting with the largest and decreasing in size to smallest dimension.

Installing the Pinion Gear

Camshaft Shims

Camshaft shims (6769 & 6770), used to control maximum camshaft end play were discontinued in 1982 production engines. It was determined through engineering testing that an increase in the maximum allowable cam gear shaft end play does not contribute to an increase in noise or prove to be detrimental to component operation. 18)

When reassembling engines after service or repair, it isn't necessary to re-install the camshaft shims. The cam gear shaft end play should be measured following the procedure in your FSM. Observe the minimum end play specs of 0.005“ for all cam gears, except rear intake which is 0.004” min. end play. It is no longer necessary to measure maximum cam gear shaft end play. 19)

Gearcase Cover

Sub-Documents

Caution: Improperly intermixing components can cause loss of top­ end oil pressure and subsequent damage. After replacing any of these components, check top-end oil circulation to ensure proper operation.

Late 1981 and Early 1982 engines may have one of two dif­ferent types of gear case cover and crankcase set combinations. 20)

The early style cover, of course, was designed for use with the early style crankcase using the required early style gasket. But, it will also fit the late style crankcase while using the early style gasket.

The late style cover will not work with the early style crankcase and the late style gasket must be used with it.

Old crankcase has a small boss with an oil trough (top center) on the cover mounting flange.

New crankcase has a larger boss with an oil hole (top center) and an extra threaded mounting hole (top left) in the flange.

Old style gasket (25224-52A) has a short slot (top center) at the oil hole location.

New style gasket (25263-81) has a long slot (top center) at the oil hole location.

Old style gearcase covers (XLH 25227-81) and (XLS 25229-81) have a rubber plug on the lower left.

New style gearcase covers (XLH 25208-81) and (XLS 25209-81) replaced the rubber plug with a hex capscrew and also contains the extra mounting hole (top left).

Pinion Gear

Compatibility

Part#

Year Models

24011-37

1954-1976 KH / XL / XLH / XLCH

24059-74

1977-1978 XLH / XLCH

24055-74 (brown)

1979-1985 XL / XLCH / XLS / XLX

24056-74 (blue)

24057-74 (Red)

24058-74 (white)

24059-74 (green)

24060-74 (yellow)

24061-74 (black)

Tappets (Lifters)

Reports were received indicating that tumbling stone contamination may have been existent in Late 1982 - Early 1983 engines with crankcase VINs (782025001-783200001). Tumbling stones are used in the polishing process of tappet bodies and occasionally can become wedged within the tappet body. The retention of a tumbling stone in the tappet assembly will cause premature tappet wear. If contamination has occurred and tumbling stone material is allowed to circulate through the engine for an extended period of time, some engine damage will eventually occur. Affected engines will first show excessive wear of one tappet guide assembly. 21)